In Fiber-to-the-Premises broadband network applications optical splitters are used to split the optical signals at various points in the network. Recent network specifications call for optical splitters to be incorporated in fiber distribution hubs (FDHs) which are re-enterable outdoor enclosures. These enclosures allow easy re-entry for access to optical splitters allowing splitter ports to be utilized effectively and for additional splitter ports to be added on an incremental basis.
In typical applications to date, optical splitters are provided prepackaged in optical splitter module housings and provided with splitter outputs in pigtails that extend from the module. The splitter output pigtails are typically connectorized with high performance low loss SC or LC connectors. This optical splitter module, or cassette, provides protective packaging for the optical splitter components in the housing and thus provides for easy handling for otherwise fragile splitter components. This approach allows the optical splitter modules to be added incrementally to the fiber distribution hub, for example, as required.
A problem may arise due to the lack of protection and organization of the connectorized ends of the splitter output pigtails. For example, these pigtails can sometimes be left dangling in a cable trough or raceway within the enclosure. This method of leaving an exposed optical component such as a high performance connector exposed in an open area leaves it susceptible to damage. These high performance connectors if damaged can cause delays in service connection while connectors are repaired. Leaving connectorized splitter output pigtails dangling in a cabling trough also exposes them to dirt and debris in the cabling trough. In current network deployments it is imperative to maintain clean optical connectors to maximize the performance of the network.
In addition, the. fiber pigtails in the current art are not organized in a manner conducive to rapid service delivery. In many cases splitters may have sixteen or thirty-two output pigtails bundled together making it difficult to find a particular pigtail. Also the bundle of loose hanging pigtails can easily become entangled causing further delays in service delivery. These tangles can actually cause congestion and in some cases resulting in bend induced loss on the pigtails causing lower system performance.
To solve some of these issues a separate storage tray or enclosure has been utilized to take up slack and/or store and protect splitter output pigtail connectorized ends. However, these auxiliary devices tend to take up additional space and often hide the pigtail in an enclosure that can cause further delays in deployment depending on how much time is required to access on the tray or enclosure. Thus, there still remains a need for a solution that does not take up additional space and that provides direct access and identification to splitter output pigtail ends.
In addition, some network applications may require equipping splitter outputs with fiber optic terminators in order to reduce or eliminate reflections caused by unterminated splitter outputs. Other methods of storing connectorized pigtails in cable troughs or auxiliary trays may make it difficult to equip splitter output ports with fiber optic terminators.
Finally current methods tend to result in a disassociation of the splitter module from the splitter output pigtail end. This usually results because the pigtail, once deployed, gets lost in the midst of other pigtails in the fiber jumper trough. When subscribers are taken out of service it is desirable to disconnect the splitter output and redeploy or store it for ready redeployment. It is further desirable for administrative purposes to maintain association of splitter module to splitter output pigtails so that resources are used effectively over time.
Fiber distribution hubs may be located at, or near, ground level or they may be affixed near the top of utility poles. Since FDHs are often located outdoors, the enclosures must be weather proof. And, reducing the number of seams in the exterior of the FDH reduces the chances of moisture penetration thus helping to provide a weather proof interior volume for the enclosure. As a result, most FDHs are accessible from only a front face by way of a door. Therefore, servicing connectors located behind a bulkhead can be problematic since removal of the bulkhead may be required. Bulkhead removal becomes increasingly difficult as service providers attempt to increase the number of connectors, or drops, located within a single enclosure. As the number of drops increases, enclosure size and bulkhead size increase. In addition, the weight and complexity of cabling may increase.
When FDHs are mounted on utility poles, large panel sizes can become unwieldy for linesman because the door must be swung open to gain access to the enclosure interior while the linesman is tethered to the pole and/or enclosure. In order to accommodate linesman, many pole mounted FDHs are equipped with balconies for providing a surface on which the linesman can stand while working inside an enclosure. A linesman typically climbs a ladder until he can step onto the balcony. Transferring from the ladder to the balcony while wearing a tool belt can be cumbersome and dangerous. Safety procedures dictate that the linesman attach a fall restraining line, or safety line, from his safety harness to a structure on the pole before transferring from the ladder to the balcony. In some instances, a linesman may connect his safety line to a structure that is not rated for stopping his fall.
What is needed are FDHs that are designed to be easily accessible from ground level and when working on elevated platforms such as utility poles. These FDHs should provide for efficient deployment and interconnection of fiber optic connections therein. Furthermore, FDHs should allow a linesman to open the enclosure without undue risk of losing balance and internal bulkheads should facilitate easy and safe access to connectors located in the rear of the FDH. Pole mounted FDHs should further be configured so as to minimize the chances of having a linesman attach a safety lead to a structure not rated for stopping a fall.